In dialysis systems including sorbent based systems, certain amounts of gas such as carbon dioxide can be created by the breakdown of urea into ammonia and carbon dioxide by urease. The resulting gas can go into solution in a fluid such as a dialysate and/or form gas bubbles. The bicarbonate buffer system can also contribute to the creation of excess carbon dioxide in dialysis fluid. Removal of carbon dioxide and other dissolved and undissolved gases in a dialysis system can be important in order to maintain a required pH, certain fluid conditions such as bicarbonate or ion concentration, and avoid the creation of gas bubbles. For example, a desired partial pressure of carbon dioxide may be required for safe operation of dialysis. Additionally, gas bubbles can interfere with the smooth pumping of the dialysate in the dialysate loop, interfere with sensors in the dialysate flow loop, reduce diffusive clearance across the dialysis membrane, and can present a dangerous condition for a patient if the gas crosses the dialyzer membrane into the extracorporeal circuit and causes gas bubbles in the blood returning to the patient.
However, the water used to initially prepare a dialysate may contain a significant amount of dissolved gases, such as nitrogen and oxygen. Further, carbon dioxide may be formed as part of the breakdown of urea as spent dialysate flows through the sorbent cartridge. Dissolved gases may come out of solution in the dialysate flow loop, creating bubbles and interfering with sensors and the ability of the pumps of the dialysis system to smoothly pump fluid. In addition to carbon dioxide from the breakdown of urea, dialysate can also contain dissolved oxygen and nitrogen gas that crosses the dialysis membrane from the patient's blood.
The degassers known in the art do not necessarily efficiently remove dissolved gases, such as carbon dioxide, from fluid, or do not provide control over the amount of carbon dioxide removed. Hence, there is a need for a degasser that can remove large amounts of dissolved carbon dioxide from solution, while providing control over the amount of dissolved and undissolved gases removed from fluid before, during and after dialysis therapy. There is also a need for a degasser having the small size and weight necessary for a portable device.